Field of the Invention
The present invention relates to a radiation imaging apparatus, a radiation imaging system, a radiation detection apparatus, an imaging control apparatus, an imaging control method, and a storage medium.
Description of the Related Art
In recent years, a digital radiation imaging apparatus that performs imaging by an imaging unit which uses a photoelectric conversion element has become popular in radiation imaging for medical diagnostic purposes. Since a radiation fluoroscopic image can be obtained without having to develop a film or the like, the digital radiation imaging apparatus has immediacy and is superior in terms of its ability to perform image processing and the like.
In the digital radiation imaging apparatus, there is also provided an automatic exposure control (AEC) unit that includes an AEC detector for the purpose of minimizing radiation exposure to the human body in addition to appropriately irradiating an object with a radiation dose necessary for the imaging apparatus. The automatic exposure control unit is sometimes referred to as a phototimer. Japanese Patent Laid-Open No. 2002-45354 discloses a technique for grasping and controlling the radiation dose by nondestructively reading out the radiation that enters the photoelectric conversion element without using a phototimer. Japanese Patent Laid-Open No. 2004-166724 discloses a technique for calibrating the output of a dose grasping photoelectric conversion element in accordance with a grid.
In a conventional apparatus, a dose grasping pixel has a different usage history compared to an image capturing pixel and requires a higher frequency of output value calibration than the image capturing pixel in terms of the influence of temporal change in cases of long term use, installation of the radiation imaging apparatus, and periodic maintenance. If the frequency of calibration is to be higher, an output value calibration of the dose grasping pixel that can be performed more simply from a user perspective is required.
In addition, when a scattering radiation removing grid is to be used, the characteristics of the output signals output from the pixels differ depending on the relative positional relationship between the grid pitch and the pixel pitch. Therefore, in the conventional apparatus arrangement, it is difficult to simply calibrate, by using the output signal, the output value of the dose grasping pixel in accordance with the state of usage of the radiation imaging apparatus.
The present invention provides, in consideration of the above problem, a radiation imaging technique capable of calibrating a dose grasping pixel by using the respective output values of the dose grasping pixel and image obtaining pixels in accordance with the state of usage of the radiation imaging apparatus.